Machine tool for milling tubular workpieces



May 1, 1951 B. v. MILLER MACHINE TOOL FOR MILLING TUBULAR WORKPIECES 5 Sheets-Sheet 1 Original Filed Oct. 22, 1948 MN MN 0 May 1, 1951 B. v. MILLER MACHINE TOOL FOR MILLING TUBULAR WORKPIECES 3maentor Gttornegs m A N Q N 5 m Wm Original Filed Oct. 22, 1948 May 1, 1951 B. v. MILLER MACHINE TOOL FOR MILLING TUBULAR WORKPIECES 5 Sheets-Sheet 5 Original Filed Oct. 22, 1948 mg N m m WWW W I m m H 3 QQ M M H \& M V ////7//// w\\ r WW Q Q 4 6 m Q mQ\ -v Q M\ vim. 3 Qm riiza Mm R sw mm *6 mm Q mm m@ o5 R n m% \wu.\\ RR 9v m mm M v R N. m. \m. \N WN I|N|L| Q m NM. mu 0 WW R9 9 MN m NM 3 mw m ////4 4/ %N mm m MN h RN KN M. QM. R Q om.

May 1, 1951 B. v. MILLER ,3

MACHINE TOOL FOR MILLING TUBULAR WORKPIECES- Original Filed Oct. 22, 1948 5 Sheets-Sheet 4 4540 SCREW war E/VGA61;D 43 25 154w sceevv NUT agave/4&5?)

Zea s/vmm Q Imventor 5527' V. MILIEQI (Ittomegs May I, 1951 Y B. v. MILLER ,3

MACHINE TOOL FOR MILLING TUBULAR WORKPIECES I Original Filed 001;. 22, 1948 5 Sheets-Sheet 5 W GEM 650R EEDUCEE,

oms'eewvm/vq 53 farm c; S8660 cam/v6: 664k CARR/665 /vz/7 1540 .S R \7/ Zmventor Gttomegs Patented May 1, 1951 MACHINE TOOL FOR MILLING TUBULAR WORKPIECES Bert V. Miller, Memphis, Tenn., assignor to Layne & Bowler, Incorporated, Memphis, Tenn., a corporation of Delaware Original application October 22, 1948, Serial No. 55,954, now Patent No. 2,526,762, dated October 24, 1950. Divided and this application November 5, 1949, Serial No. 125,762

7 Claims. (Cl. 90-11.44)

This invention relates to machines for processing cylindrical Work pieces, such as tubing or pipe, and particularly relates to a machine adapted to face the opposite ends of such work piece and to mill threads therein, and is a division of my pending application for patent on a Machine Tool for Milling Tubular Work Pieces, Serial Number 55,954, filed October 22, 1948, now- Patent No. 2,526,762 issued October 24, 1950.

It has long been considered desirable to mill the threads of cylindrical work pieces such as tubing or pipe because of the improved accuracy of threading formed by the milling process. It has also been recognized that it is desirable to concurrently form the threads on the opposite ends of such work piece, thereby insuring axial alinement of such threads.

' Many attempts have been heretofore made to accommplish such desired threading, but the means by which such result has been attempted to be accomplished have primarily been unsatisfactory because of their incorporation of an undesirable number of mechanisms, and because of their inability to perform the function for which designed, through inaccuracies in coordination.

The machines heretofore devised have essentially been provided for accomplishin concurrent threading of the opposite ends of the work piece by mounting the work piece for revolution in a position fixed against longitudinal movement relative to the machine and have employed machine elements carrying threaded tools or hobs positioned eccentrically of the work piec in cutting engagement with one side of the periphery thereof and mounted for longitudinal shift relative to the work piece as the revolution of the work piece has progressed. As will readily be seen, when concurrent threading of the opposite ends of the work piece has been undertaken it has been necessary to employ two cutters and to concurrently shift the two cutters during the revolution of the work piece, resulting in an excess of mechanism, and requiring an accurate coordination which has not been achieved.

The present invention is designed to simplify the means by which concurrent threading of the opposite ends of a work piece may be accomplished and to accurately coordinate the elements of the machine, and in general difiers from the machines known in the art in providing for longitudinal movement of the work piece during revolution thereof, such longitudinal work-piece shift being accomplished relative to the fixed cutting position of the spaced tools and in coordination with the'aforesaid revolution. In accomplishing this object th present invention makes use of a new and novel work holder means by which the workpiece revolution is accomplished, and shift ertne work piece accurately coordinated with the'work revolution, is eifected.

This divisional application relates'particularly to stop means by which approach of the work carriage tothe tools, or of the tools to the work carriage, is -limited, and to means in connection therewith bywhich displacement of the tools is allowed should overtravel of the work carriage toward the tools, or overtravel of the tools toward the work carriage, occur.

The principal object is to provide in a machine tool assemblyfwhich includes a pair of tool holders adjustable longitudinally and transversely of the machine and rotatable in a fixed position, and a longitudinally shiftable work holder which includes means-for holding and revolving a work piece and means coordinated with such revolution for gradually longitudinally shifting said work piece a predetermined limited distance relative to said tool holders, means for limiting the relative approach of the work holder and the tool holders;

To provide a longitudinally shiftable work holding carriage, cooperative tool holding carriages longitudinally adjustable toward and away from said work carriage, means for'displaceably holding said tool carriages in adjusted positions, and means for limiting relative approach of said work carriage to said tool carriages;

To provide a longitudinally shiftable work holding carriage, cooperative longitudinally shiftable tool holding carriages, adjustable means for limiting relative approach of said work carriage to said tool carriages, means for advancin said tool carriages toward said work carriage and yieldably holding said tool carriages in said advanced positions; and

A further object of the invention is to generally improve the design, operation and efliciency of machine tools, particularly those adapted to process cylindrical work pieces.

- The means by which the foregoing and other partly in section, showing further details of the.

arrangement of the parts of the present invention.

Fig. 4 is an enlarged sectional elevation taken on the line IVIV of Fig. 2 showing detail of the lead screw nut clamping parts Fig. 5 is a schematic elevational view showing the relative positioning of the work and the facing portion of the threading hobs, as facing of one end of the work piece is completed and the related stop limits further facing action.

Fig. 6 is a schematic sectional plan view showing the relative positioning of the threading hobs and the work as the threading operation begins.

Fig. '7 is a companion view showing relative positioning at the completion of the, threading operation.

Fig. 8. is an end elevation of the threading and facing hobs; and

Fig. 9 is a schematic drive diagram illustrating the operation of the present invention.

Referring now to the drawings in which the various parts are indicated by numerals:

The machine illustrated is one which is particularly adapted for milling a cylindrical work piece as the tubing I and is so arranged that the ends of the tubing may be faced by the machine and subsequently the opposite ends of the tubing simultaneously threaded, the threading through the arrangement ofthe present invention being in axial alinement.

The machine primarily consists of a bed II which may be supported upon suitable supports I3, upon which bed the various elements of the present machine are mounted and supported. The bed includes side walls I which at their upper ends carry ways I"I, tl e ways being also dis-. posed longitudinally of the machine and being adapted to have slidably mounted thereon the,

carriages for the various elements of the machine.

Adjacent the opposite ends of the bed, tool carriages I8, I9 are mounted slidably. upon the ways I! and are adapted for longitudinal movement along the ways for adjustment, of the relative positions of the carriages and the tools carried thereby upon the machine. Intermediate the tool carriages I8, IS a work carriage 2| is mounted. slidably upon the ways H. In general, the work piece It to be processed is handled by the mechanisms associated with the work car- 25 by belts 21 and pulleys 28 to effect rotative drive of the spindle. It will be understood that the motor and coupling illustrated is a preferred form of drive for the spindles, but that any suitable means for rotating the spindles may be employed if desired. It also is preferred that the motors be controlled by a single control, although obviously separate controls may be employed if desired.

Positioning of the tool carriages on the ways I! is maintained by clamps 29, each of the carriages being coupled to a clamp 29 by hydraulic cylinder and piston means which include cylinders 3I and projecting piston rods 33, the cylinders being in communication with a suitable source of fluid pressure, not shown. The projecting end of each of the piston rods is attached; to its; related tool carriage and the opposite end of each of the cylinders is anchored to its related clamp 29. The clamps 29 are preferably removablyfixed to the bed I I, as by bolts or other suitable means, such removable attachment enabling the use of the machine for work pieces of various lengths.

Movement of the tool, heads 23 transverse the machine is accomplished by cross feed screws which are preferably provided with hand wheels 31 and which also-each preferably have a suitable calibrated gage or dial and indicater 39 associated therewith for the accurate determination of the amount of transverse movement of riage and the processing tools areassociated with I thetool carriages. V g

The tool carriages I8, I9 and the elements associated therewith are substantially identical and accordingly description of one of the carriages and its associated elements is deemed sufilcient to describe the operation ofboth.

Mounted on each tool carriageior movement transversely. of the machine is a head 23, upon which head a spindle 25, axially parallel with the longitudinal center line of the machine, is mounted for rotation. A motor 26- is mounted upon the carriage and is coupled to the spindle the tool heads. The cross feed screws 35 each threadedly engage a head nut 40 on each of the heads 23 to accomplish the transverse movement in substantially conventional manner. At its inner end opposite to the attachment of piston rods 33 each of the tool carriages is provided with a forwardly projecting stop member 4| adjustably threaded on a threaded rod member 42 rigidly attached to the tool carriage.

Mounted co-axially with the spindles 25 for rotation thereby are the cutter tools 43. Each of the cutter tools is preferably provided with a shank 45 adapted to engage the socket (not shown) of spindle 25 and to be fixed therein in suitable manner. As will be seen from Figs. 4, 5 and 6, the preferred form of; cutter tool 43 is a four zone tool including a facing zone 46, an undercutting zone 41, a threading zone 48, and a blanking zone 49. It will be, seen that in its preferred form the blanking zone 49 is fluted as at 49A and has the general characteristics of a blanking mill; that the threading zone- 48 is essentially a multiple ring tooth cutter section, fluted as at 48A and serrated between the flutes at 48B, the, threading section havin no lead or pitch and in general having the characteristics ofa thread mill. or hob. It will also be noted that the outside diameter of the blanking zone 49. is substantiallyequal to the tool diameter at the root of the thread serrations. The undercutting zone; 41. is fiuted as at 41A and is of the same general characteristics as the blanking zone 49, except that it will be noted that the outside diameter. of the, undercutting zone is substantially equal to the outside diameter of the threading zone. It will; be noted, also that the diameter of the facing zone 46 isv substantially equal to,

or very slightly greater than, the diameter of the work piece tobe processed by the machine and is considerably in excess of the diameter of the blanking, threading and undercutting zones. The facing zone, is. toothed as at 46A, to give it the general characteristics of a facing mill.

Mountedupon the work carriage 2I is a housing 59 having an integral base 5| which is seated on and rigidly secured to the work carriage 2|. Carried by the housing 59' are longitudinally spaced thrust bearings 52, in which a hollow spindle 53 is journalled for rotation. The spindle 53 is provided at its opposite ends with suitable work holding means, as chucks 54, and is axially alined with the longitudinal center lines of the machine and adapted to receive and hold the work piece If! for processing by the machine. Rotation of the work spindle 59 and work piece carried thereby is accomplished preferably by motors 55, 55, mounted on the upper portion of a platform 51 rigidly secured to and supported from the work carriage 2|. The motor 55 is preferably coupled by suitable belt and pulleys to a worm gear reducer 58, preferably mounted on a lower portion of platform 57!, by which reducerthe motor speed is reduced and through which drive of a shaft 59 by the motor is accomplished. The shaft 59 is coupled by an overrunning clutch 9| to the main shaft 63, which main shaft is provided at its forward end with a worm 65. Engaged by the worm 65 is a worm wheel 91 surrounding and keyed to the spindle 53, so that upon rotation of the shaft 63 and of the worm 95 carried thereby rotation of the work spindle 53 is accomplished. Through this arrangement the motor 55 is enabled to rotatively drive the spindle 53 at an extremely low speed which is preferably in the nature of one R. P. M., and which speed is preferably employed in connection with the concurrent processing of the opposite ends of the work piece I9 by the threading, blanking and undercutting zones .of the tools 43. The rate of speed is determined by the material and the diameter of the work piece to be processed.

It is preferred that the motor 55 be provided to drive the work spindle 53 at a greater speed for processing of the work piece by the facing mill zone 49 of the tools 43. The motor 56 is coupled by suitable belt and pulleys to the shaft 93 forwardly of the overrunning clutch 9| and is adapt ed upon operation to effect rotation of the spindle 53 at a speed substantially in excess of that drive from the motor 55. It will be noted that by the coupling of the motor 53 to the shaft 63 forwardly of the overrunning clutch 6| the coupling between the shafts 59 and 69 is not effected during operation of the motor 56.

Surrounding and keyed to the spindle 53, preferably adjacent the worm wheel 6?, for rotation with the spindle is a bevel gear 59. Drivingly engaged by the bevel gear 99 is a second bevel gear 7! carried by the upper end of a stub shaft i3, the stub shaft '33 being journalled in a suitable bearing carried by the housing 59. Below and exterior the housing 59 the stub shaft 13 carries at its opposite end a small bevel gear T! which drivingly engages a similar small bevel gear 19 carried by one end of a shaft 8|.

The opposite end of the shaft 8! is longitudinally slidable in a sleeve 83. In the embodiment shown, it will be seen that the shaft BI is squared as at EMA, the interior of the sleeve 89 being of similar interior shape and being engaged by the portion 92A to insure rotation of the sleeve 93 with the shaft 9! It will be understood that the sleeve 83 may be splined to the shaft 9! or otherwise secured for rotation while permitting longitudinal sliding therewith in other suitable manner.

Similarly engaged by the opposite end of the sleeve 93 is one end of a shaft 85, which, as shown, is preferably square as at 85A to engage the interior of the sleeve 83 for rotation therewith and to be longitudinally slidable relative thereto.

It will be seen that the bevel gears 69, H are substantially equal in size and that the small bevel gears TI, 19 are also of substantially the same size, so that the rotation of shaft 85 is in equal ratio to the speed of revolution of the work spindle 53. The shaft 85 extends into a change gear box 91 by which the shaft 85 is coupled to gear train 89 and through gear train 89, and suitable gearing 99 to a longitudinally extending lead screw 9|, which has an extended threaded portion 92 intermediate its length. Through the change gear box the speed imparted to the shaft 85 is further reduced or controlled in desired manner so that the revolution of the lead screw 9| is exactly coordinated to the speed-of the work spindle revolution. Lead screw 9! is supported by and coupled into the gearing 99 at one end of the machine, and is journalled in a suitable bearing (not shown) attached to the opposite end of the machine.

A pair of depending brackets 93 are rigidly secured, as by suitable bolting, to the underside of the work carriage 2|, adjacent its forward edge, but spaced rearwardly therefrom. The brackets 93 are longitudinally spaced apart and carry adjacent their lower ends thrust bearings 94 in which a carriage nut 95 is journalled. Carriage nut 95 is interiorly threaded and threadedly engages the threaded portion 92 of the lead screw 9|. Integral with the brackets 93 are braces 96 which are connected by an integral cross member 91.

Surrounding the carriage nut 95 between the brackets 93 is a tube 98 which is adapted to engage the carriage nut and effect carriage movement thereby responsive to lead screw revolution. The tube 98 is provided with forwardly projecting lips 99 which underlie the cross member 91. The tube 98 is resilient, the resiliency urging the lips 99 to separate and upon separation of the lips the carriage nut 95 may turn freelywithin the tube 98 while closing of the lips effects clamping of the carriage nut by the tube to prevent independent nut rotation.

Preferably the upper lip 99 is provided with an integral pad 99A which is contacted by the lower lip during clamping to insure a more solid seat. It is also preferred th t separation of the lip be limited and for that purpose an adjustable limit, as screw 99B is provided, extending loosely through a suitable aperture in the lower lip into threaded engagement with the upper lip or its pad. It will be seen that the lead of the screw is spaced from the upper lip sufficiently to permit opening of the lips to disengage the. tube 98 from carriage nut 95.

When nut rotation is prevented by tube engagement, revolution of the lead screw will cause the nut to advance longitudinally thereof, and it will be seen that rotation of the nut at a speed in excess of the speed of lead screw revolution may be employed to advance the nut in the direction of the lead of the screw, while advancement in the opposite direction may be effected by overriding the lead screw revolution. Both the latter nut movements may be effected through the controls employed herein. Support and mounting of these controls and of the means for effecting closure of the tube lips 99 are provided by a frame work which consists of an upper horizontal bar I09, which is rigidly attached to the underside of work carriage 2|, and extends longitudinally thereof abutting the forward edges of access:

brackets 93. Integrated as by welding with the upper bar I are. vertical end bars IDI which depend from the upper bar. A lower bar member I02 spans between the vertical bars I0I and is preferably secured thereto at its opposite ends asv by welding, the opposite points of securing. being preferably spaced above the lower ends. of the vertical bars. Seated on and rigidly secured to, the lower bar I02 are intermediate vertical members I03. which extend upward to the upper bar I00 and. are rigidly secured thereto. Extending between the upper and. lower bars I00, I02, and from one intermediate bar I03 to the other and rigidly secured to each of the bars is a plate I04, which is provided with an inwardly extending ear I05 secured as by bolt I 06 to the cross member 91.

Control of the closure of lips. 99 is effected through a hand lever I01 carried exterior the cover plate I04, which is rigidly secured to the outer end of'a stub shaft I08. Shaft IDS is journalled in a suitable bearing in plate I04 and at its inner end has a cam I09 rigidly secured thereto in eccentric relation. The cam I09 underlies the lips 99, as shown in Fig. 4, the lower lip. not being engaged by the cam and being urged by the resiliency of the tube. to move away from. the upper lip, freeing the carriage nut 95 from engagement. by the tube 98.

When the hand lever I01 is depressed substantially to a horizontal position the cam I09 is. moved into engagement with the lower lip 99, moving that lip toward closed position and effecting engagement by the interior of the tube 98 with the exterior of the carriage nut 95, holding the tube clamped in this engagement. It will thus be seen that upon rotation of the lead screw- 9I in coordination with the revolution of the work spindle 53, the carriage nut 95 in threaded engagement with the lead' screw will turn freely with the lead screw so long as the tube 98 remains out of clamping engagement with the carriage nut. When the hand lever I0! is depressed and the cam I09 moved into engagement with the lips of the tube 98', the carriage nut is held against rotation with the lead screw and drive of the lead screw by the Work spindle will consequently effect advancement of the carriage nut' thereon, such advancement carrying with it the work carriage 2| and the instrumentalitiesv associated therewith.

Keyed to the carriage nut 95 beyond the. right hand bracket 93 is a first bevel gear, not shown, with which a second bevel gear, not shown, is engaged. The. second bevel gear is carried by the inner end of a shaft I I2, also suitably journalled in and extending through plate I04, to the outer end of which shaft a control, as a suitable hand wheel- H3, is attached. Through. the means of the hand wheel and the interengaged'bevel: gears, manual longitudinal movement of the work carriage may be accomplished, rotation of thefirst bevel gear effecting rotation of the second bevel gear and consequently rotation of the carriage nut 95. Through the employment of this manual means the work carriage may be longitudinal}- ly shiftedwhether the lead. screw is in revolution or at a standstill, as described above.

Selective operation of motors 55, 56, is. accomplished. through a suitable rotary switch housed in a switch box H4 and electrically connected to the respective motors. A contact arm, not shown, is mounted within the switch: box and is attached to; one end: of an elongatedrod H5. Intermedi-= ate its length rod H5 is journalled in and sup ported by the lower extension of end barsv NH, and carries at its opposite. end a bevel gear II6 which is engaged by av similar bevel gear I I1 carried by a short control rod I I8. The control rod is suitably journalled in the projecting legs of a U -shaped bracket I I9, rigidly attached preferably to the right hand end bars IOI. A control. lever I20 is. attached to the upper end of control rod I I8. It will be seen that movement. of lever I20 will rotate. rod I18 and gear II'I, effecting equal rotation of gear I I6 and switch rod I I5, the switch contact arm being swung thereby from one contact. to another as desired.

In the operation of the device, the tool carriages I8, I9 are. positioned on the ways I! and spaced apart a distance to accommodate the length of the work piece to be processed thereby, with the piston rods33 respectively fully extended from their cylinders 3 I. When so positioned the clamps 29 are rigidly attached to the bed I I, thus anchoring the tool carriages at their extreme inward position of longitudinal movement and the threaded stops. 4| adjusted on their rods 42 to establish a space between the stops determined bythedesired finished length of the work piece. The piston rods 33 may then be retracted moving the tool carriages longitudinally outwardly. The heads 2-3 are moved transversely rearwardly of the machine by the cross feed screws 35, clearing the work spindle 53 for the insertion of the work piece I0 therein. The work piece I0 is inserted in the spindle and engaged by the chucks 54, the tool carriages are returned transversely of the machine to bring the tool spindles 25 and the tools 43 carried thereby into axial alinement with the work piece I0. In the embodiment shown, the-facing zone 46 of each of the tools 43 is thus alined for milling the opposite ends of the work piece I0.

The tool motors 26 are energized, rapidly rotating the cuttertools 43 at cutting speed. The motor 56 may then be energized through the operation' of switch control I20 beginning revolution of the work spindle 53 through the drivehereinabove described and the work carriage 2| manually shifted through the operation of the. hand wheel M3 to bring one end of the work piece It into engagement with the facing zone of one of the cutters 43. It. will be noted that the stop 4'I is: in alinement with the base 5| of the work carriage, so that excess shift of the carriagebeyond' the desired distance will cause abutment of the stop by the base, preventing any damage to the work piece or to the tool by maintaining the spacing established. If any further excess shift is attempted" the entire tool carriage is moved therewith against the effect of the associated cylinder and piston 3|. Preferably thisv initial position is that; illustrated in Fig. 5 of the drawings in which the work carriage 21 has been shifted to the right to bring the end of the work piece into engagement with the facing zone of the cutter. When facing one end of the work piece has thusbeen accomplished the work carriage is,

through operation of hand wheel II3, manuallyshifted in the opposite direction to bring the oppositeend of the'work piece I0 into facing contact with the opposite tool 43.

When the end facing of the work piece has been completed the tool carriage is minutelybacked off manually to the position shown in Fig. Gin which the work piece is just clear of the facing zone 46 of 'the left hand tool 43 and out of: contact" therewith.

The motor 56 is deenergized and low speed motor 55 is energized through the selective control I29 to drive the work spindle 53 at the low speed hereinabove described. When the low speed motor has taken over the drive of the work spindle, the hand lever I! is depressed moving the cam "39 into engagement with the lower lip 99 and effecting clamping by the'tube 9B of the carriage nut 95. The tool heads 23 are shifted forwardly by the operation ofthe cross feed screws 35, thus moving the tools 43 to a position eccentric of the work piece It] and bringing the undercutting, threading and blanking zones '41, 48, 49 into cutting engagement with the interior of the work piece [0, this transverse movement being continued until the tools are moved in to the full depth of cut desired. The amount of this latter transverse shift of the tool heads may readily be accurately determined from the gage 39.

The three zones 41, 48, 49 of each of the tools simultaneously operate upon the work piece and during such operation are rotated in a fixed position. While the tool are being rapidly rotated, the work piece I!) is revolved, as previously described, such revolution, through gears 69, H, 15, 11, shafts BI, 85, change gearing 81, and gear train 89 effects coordinated revolution of lead screw 9|. The work carriage nut 95 is held against rotation by the clamped tube 98 and through the engagement of the nut, with the lead screw 9| the work carriage and work piece carried thereby are moved steadily along the bed longitudinally of the machine, in the present instance being shown as moved from left to right. Through the coordination of the lead screw drive with the work spindle revolution the work carriage is moved a distance equal to the lead of the thread desired during one revolution of the work spindle so that a complete helical thread having the desired lead is simultaneously formed in the opposite ends of the work piece.

As the threading operation is accomplished the blanking zones 49 form a milled finish surface inwardly of the threaded zones of the work piece and the undercutting zones 4'! form a'suitable undercut zone adjacent the ends of the work piece. When the processing operation has been completed the tool heads 23 are moved transversely a minor distance until the tools are clear of the work piece, at which time the tool carriages l8, I9 may be retracted by the cylinders 3| and piston rods 33, moving the tools out of the work piece. The tool carriages may then be again moved transversely of the machine rear- Wardly and the work piece removed from the work spindle.

It will be understood that when processing of larger or longer work pieces is desired adjustment of the spacing of the carriages in the manner described may be made. When a work piece of excessive length is to be handled suitable steady rests may be employed for support of the work piece intermediate the tools and the work spindle.

I claim:

1. In a machine which includes a bed, a work carriage shiftable longitudinally of said bed and means for effecting said longitudinal shift, a tool carriage slidably mounted on sai d bed, hydraulic means yieldably anchoring said tool carriage in operating position on said bed, and a stop member adjustably attached to said tool carriage and projecting toward said work carriage in alinement therewith, said stop member work carriage shift toward said tool carriageto maintain spacing between said carriages.

2. In a machine which includes a bed, a work carriage shiftable longitudinally of said bed and means for effecting said longitudinal shift, a tool carriage slidably mounted on said bed, means yieldably anchoring said tool carriage in operating positionon said bed, and a stop member adjustably attached to said tool carriage and projecting toward said work carriage in alinement therewith, said stop member being adapted to abut said work carriage during work carriage shift toward said tool carriage to maintain spacing between said carriages.

3. In a machine which includes a bed, a work carriage shiftable longitudinally of said bed and means for efiecting said longitudinal shift, a tool carriage slidably mounted on said bed, means yieldably anchoring said tool carriage in operating position on said bed, and a stop member attaching to said tool carriage and projecting toward said work carriage in alinement therewith, said stop member being adapted to abut said work carriage during work carriage shift toward said tool carriage to maintain spacing between said carriages.

I 4. In a machine which includes a bed, a work carriage shiftable longitudinally of said bed, and means for eifecting said longitudinal shift, a tool carriage slidably mounted on said bed, a shiftable clamp rigidly secured to said bed, hydraulic cylinder-piston means interposed between said tool carriage and said clamp and oppositely secured to said tool carriage and said clamp, yieldably anchoring said tool carriage in operating position on said bed, and a stop member attached to said tool carriage and projecting toward said work carriage in alinement therewith, said stop member being adapted to abut said work carriage during work carriage shift toward said tool carriage to maintain spacing between said carriages.

5. In a machine which includes a bed, a work carriage shiftable longitudinally of said bed and means for effecting said longitudinal shift, a tool carriage slidably mounted on said bed, a shiftable clamp rigidly secured to said bed, yieldable means interposed between said tool carriage and said clamp and oppositely secured to said tool carriage and said clamp, yieldably anchoring said tool carriage in operating position on said bed, and a stop member attached to said tool carriage and projecting toward said work carriage in alinement therewith, said stop member being adapted to abut said work carriage during work carriage shift toward said tool carriage to maintain spacing between said carriages.

6. In a machine which includes a bed, a pair of tool carriages spaced apart and slidably secured on said bed, a work carriage mounted on said bed between said tool carriages and shiftable longitudinally of said bed toward and away from said tool carriages, and means for effecting said longitudinal shift, anchoring means for each respectively of said tool carriages rigidly secured to said bed, hydraulic cylinder-piston means, each respectively operatively coupling a said tool carriage to its related said anchoring means, sto-p members adjustably attached each respectively to a said tool carriage and projecting toward said work carriage in alinement therewith, said stop members being adapted to abut said work carriage during work carriage shift toward said tool carriage to maintain spacing between said carriages.

1 2,551,381 1:1 12 7. .In a machine which includes a bed, tool car- REFERENCES CITED n'age means slidably secured on said bed, .a work I carriage mounted on said bed and shiftable loni :f;; f:. are of record m the gitudinally of said bed toward and away from said tool carriage means, and means for effecting said 5 UNITED STATES PATENTS longitudinal shift, anchoring means for said tool b r ame Date carriage means, and yieldable means, operatively 779,251 Baggaley Jan. 3, 1905 coupling said tool carriage means to said anchor- 863,681 Warner Aug. 20, 1907 i 8 means. 4 1,340,811 Ballman May 18, 1920 BERT V. MILLER. 10 1,978,879 Ferris et a1 Oct. 30, 1931 2,321,822 Kendis June 15, 1943 2,346,516 Steinle et a1 Apr. 11, 1944 

